1. Field of the Invention
The present invention relates to cell-based wireless networks (such as those based on GSM), and more specifically to a method and apparatus for extending multicast applications available on data networks (e.g., Internet Protocol based networks) to such wireless networks.
2. Related Art
Multicasting generally refers to sending data from one entity (machine, application, etc.) to only some of the pre-specified entities (“end entities”) in a networked environment. Multicasting is used to implement several applications (“multicast applications”) such as network-based broadcasting (to several machines/users), movies, video conferencing, etc.
Data networks have been implemented to support multicast applications. For example, IGMP (Internet group management protocol) defines a standard by which a router-type device may indicate the specific class-D addresses (with each class-D address typically providing a multicast application) of interest to one or more IP (Internet Protocol) machines on a network the router is also connected to.
The data related to such class-D addresses (indicated using IGMP) may be made available to a router, which in turn makes the data available to the machines forming the end machines of the corresponding multicast application. Thus, the end machines receive the data corresponding to the multicast applications of interest. IGMP is described in further detail in a document entitled, “RFC 2236: Internet Group Management Protocol, Version 2”, by W. Fenner, Dated November 1997, available from www.ietf.org, which is incorporated in its entirety herewith.
Cell-based wireless networks have evolved in parallel, initially to allow voice communications (akin to telephone calls). A cell-based wireless generally contains several transceiver stations, with each transceiver enabling mobile nodes (e.g., cell phones) to send and receive voice information. The signals within the cell-based wireless networks are used as a basis for enabling voice communications. GSM (Global System for Mobile Communication) is an example standard which allows such connectivity to mobile nodes. GSM is described in further detail in a book entitled, “The GSM System for Mobile communications”, by M. MOULY and M. B. PAUTET, ISBN 2-9507190-0-7, which is incorporated in its entirety herewith.
Solutions have been implemented to provide connectivity between mobile nodes and machines in data networks. For example, in GSM environment, devices commonly referred to as SGSN (Serving GPRS Support Node) and GGSN (Gateway GPRS Support Node) are employed to provide such connectivity. The corresponding solution is described in a document entitled, “3GPP TS 29.018 V4.2.0 (2001-12); 3rd Generation Partnership Project; Technical Specification Core Group Network; General Packet Radio Service (GPRS); Serving GPRS Support Node (SGSN)—Visitors Location Register (VLR); Gs interface layer 3 specification (Release 4)”, (hereafter “GPRS Document”) available from 3GPP support office address, 650 Route des Lucioles—Sophia Antipolis, Valbonne—FRANC3E, Tel.: +33 4 92 94 42 00 (ftp://ftp.3gpp.org/Specs/), which is also incorporated in its entirety herewith.
It may be desirable to extend multicast applications to mobile nodes such that users using mobile nodes can access applications such as video broadcasts. In one approach, multiple copies of data, related to a multicast application may be transmitted, with each copy being sent to a corresponding mobile node. In general, the use of such multiple copies may create an undesirable level of overhead (e.g., in terms of bandwidth requirement, processing requirements in various components).